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2.6
light
EARTHQUAKE DETAILS

3 km North-West of Forni di Sotto

48 months ago · 18 Sept, 01:32

A light earthquake, rarely felt by people. At only a few km deep the shaking is felt more sharply at the surface.

Stronger than 96% of Italian events in the past year

Where

3 km North-West of Forni di SottoEarthquakes in the province of UdineEarthquakes in Friuli-Venezia Giulia

How far away could it be felt?

A quake this small is usually not felt by people: only seismographs record it.

Statistical estimate from the Italian intensity attenuation model (INGV): actual perception depends on geology, buildings and depth. Very shallow events can be felt locally even below the threshold.

Earthquake map

32 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

120kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×4 its energy
M2this quakeM4

Each extra magnitude unit releases about 32 times more energy: an M5 is not "a bit stronger" than an M4 — it is a different league.

Energy estimated with the standard Gutenberg–Richter relation; an average lightning bolt ≈ 1 billion joules. Indicative values.

The race of the seismic waves

Two waves set off from the hypocentre: the faster P wave arrives first with a sharp jolt; the S wave carries the actual shaking.

P waves — the first sharp jolt (~6 km/s)S waves — the strongest shaking (~3.5 km/s)
t ≈ 28 s

Animation sped up ~5× compared to reality.

  • Pordenone
    52 km from the epicentre
    first tremor in ~9 s
    main shaking in ~15 s
  • Udine
    62 km from the epicentre
    first tremor in ~10 s
    main shaking in ~18 s
  • Treviso
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~25 s
  • Bolzano
    96 km from the epicentre
    first tremor in ~16 s
    main shaking in ~28 s

Theoretical times with average crustal speeds: real values vary with geology. The gap between P and S waves is what earthquake early-warning systems rely on.

How deep it was born

9 km
shallow

At only a few km deep the shaking is felt more sharply at the surface.

in line with the area average (~9 km)

For the same magnitude, a shallow earthquake is felt much more than a deep one: the energy starts closer to the surface.

What kind of quake is this?

Aftershock

It is an aftershock: it follows a stronger quake (M3.5, 49 months ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

3.5
The mainshock
3 km East of Frisanco
49 months ago · 25 Aug, 02:34
Activity in the area right now (30 km radius)
0
last 24 hours
2
last 7 days
7
last 30 days
10 before21 after
this quake
Strongest of the sequence3.5

How often does it happen here?

about every ~42 days

Within 50 km of this epicentre, a magnitude ≥ 2.5 earthquake has occurred on average this often: 102 events in the last 12 years of the INGV catalogue.

An average computed on the recent past: it tells how used this area is to shaking, not when the next quake will come — earthquakes cannot be predicted.

The great earthquakes in this area's history

Almost a thousand years of catalogues: the strongest documented events within ~50 km.

19766.5
Friuli earthquake
6 May 1976 · 43 km from here
IX-XCompletely destructive: most buildings are destroyed.
18736.3
Alpago Cansiglio earthquake
29 June 1873 · 33 km from here
IX-XCompletely destructive: most buildings are destroyed.
19366.1
Alpago Cansiglio earthquake
18 October 1936 · 40 km from here
IXDestructive: many buildings partly or fully collapse.
19286.0
Carnia earthquake
27 March 1928 · 28 km from here
IXDestructive: many buildings partly or fully collapse.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Tramonti-Montemaggiore

The epicentre lies about 14 km from Tramonti-Montemaggiore, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 6.2between 1 and 6 km deep

Faults are mapped to build better and understand the territory: knowing them says nothing about when an earthquake will occur, which remains unpredictable. Source: DISS 3.3 (INGV, CC BY 4.0).

Other quakes in the area

1.4
3 km North-East of Arba
30 km South-East · 12 km
48 months ago
17 Sept, 15:52
1.0
3 km North of Frisanco
18 km South-East · 10 km
48 months ago
18 Sept, 18:56
1.1
2 km South of Socchieve
14 km East · 11 km
48 months ago
20 Sept, 01:57
1.2
3 km South of Barcis
28 km South · 11 km
48 months ago
21 Sept, 10:34
0.6
3 km North of Frisanco
18 km South-East · 9 km
48 months ago
22 Sept, 02:27
0.9
2 km East of Cavasso Nuovo
29 km South-East · 15 km
48 months ago
24 Sept, 11:26
1.3
4 km North of Andreis
17 km South · 9 km
48 months ago
10 Sept, 11:00
1.0
48 months ago
26 Sept, 14:29
1.0
3 km North-East of Raveo
20 km East · 8 km
48 months ago
28 Sept, 22:36
0.7
3 km East of Villa Santina
28 km East · 12 km
48 months ago
7 Sept, 00:37

Data: INGV — National Institute of Geophysics and Volcanology (CC-BY 4.0)

Estimates computed by Meteare on INGV data (Gutenberg–Richter relation; Italian macroseismic intensity attenuation model).

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